Apparatus and method for heating reduced portions of adjacent workpieces



May 17, 1966 E. F. McBmEN 3,251,976

APPARATUS AND METHOD FOR HEATING REDUCED PORTIONS OF ADJACENT WORKPIECESFiled Dec. 6, 1963 FIG (PRIOR' ART) EDWARD McBRIEN FIG. 4 M75/2343?ATTORNEYS ing the shanks.

United States Patent O 3,251,976 APPARATUS AND METHOD FOR HEATING RE-DUCED PORTIONS F ADJACENT WORKPIECES Edward F. McBrien, Parma, Ohio,assigner to The Ohio Crankshaft Company, Cleveland, Ghia, a corporationof Ohio Filed Dec.` 6, 1963, Ser. No. 328,560

7 Claims. (Cl. 219--l0.69)

The present invention pertains to the art of induction heating and moreparticularly -to an apparatus and method for heating the reducedportions of adjacent workpieces.

The invention is particularly applicable for heating the reduced ends ofadjacent anged workpieces and it will be discussed with particularreference thereto; however, it-will be appreciated that the inventionhas much broader applications and may be used to heat the reducedAportions of various shaped workpieces, such as the reduced ends of axleand transmission shafts.

It is often necessary to heat the reduced portions of a workpiece suchas the shank of a flanged gear blank for the purpose of annealing orotherwise heat treating the shank. To increase the number of blankswhich can be heated in a given time, it has become somewhat commonpractice to move the gear blanks in side-by-side relationship past aninductor connected to al source of high frequency alternating current.The `gear `blanks `are aligned with the flanges of the blanks abuttingeach otherAand the Shanks extending in substantially parallelrelationship. The inductor may take a variety of congurations; however,generally the inductor is shaped to form a channel having spacedconductors extending along opposite sides of the Shanks as thegearblanks move through the inductor channel.

In this manner, the spaced conductors of the inductor induce a voltageor potential difference into the parallel Shanks, which potentialdifference causes current to flow within the Shanks. The 12R heatingeifect of these currents flowing within the Shanks heat `the Shanks tothe desired temperature. The amountof heating is `determined by avariety of factors Such as the power used in energizing the inductor,the magnetic coupling between the inductor and the Shanks, the time theShanks are within the inlluence of the inductor and the material formingthe Shanks, to name only a few.

Since the gear blanks have flanges at one end, the parallel Shanks arespaced from each other as they move through the channel inductor withthe amount of spacing being determined by the diilerence in the size ofthe Shanks and the flanges. When this spacing is large, certaindiiculties have been experienced. For instance, the only portion of theparallel Shanks which are heated with any eiciency are the portionsimmediately adjacent the inductor. .In order to heat all portions of theshank uniformly, the Shanks must be rotated so that the various portionsof the `Shanks come into proximity with the inductor. The rotation ofthe gear blanks as they pass through the channel inductor is not alwayseasy and, in some cases, it requires an external means for rotating theblanks. If the blanks are not rotated, the portions of the Shanks spacedfrom the inductor must be heated cornpletely by conduction of heatthrough the material form- This requires a substantial amount of timeand, thus, increases the expense of heating the gear blanks.

n The large spaces between the parallel Shanks leave a substantialportion of the volume within the channel inductor completely vacant.This lowers the magnetic coupling of the inductor and decreases theheating efficiency of the inductor. This lowered etliciency is morepronounced When the volume of the spaces between-the ICC adjacentparallel Shanks are quite large, i.e. when the volume of these spacesapproaches or exceeds the volume of the Shanks within the channel of theheating inductor.

All of these diiliculties and others are overcome by the presentinvention which is directed toward an apparatus and method for heatingthe reduced portions of adjacent workpieces 'which apparatus and methodincreases the etiiciency of known procedures of this type and whichreduces the need for rotating the workpieces to any great extent as theypass through the channel of the heating inductor.

In accordance with the present invention, there is provided an apparatusfor simultaneously heating the aligned reduced portions of a pluralityof side-by-side workpieces comprising an inductor having a conductor oneach side of the reduced aligned portions and a low resistivity,nonmagnetic insert between adjacent reduced portions. In accordance withthe invention, the inserts substantially lill the spaces betweenadjacent reduced portions of the workpieces.

In accordance 'with another aspect of the present invention, there isprovided a method for simultaneously heating the reduced portions of aplurality of workpieces comprising: aligning the workpieces inside-by-Side relationship with the reduced portions aligned to producespaces between adjacent workpieces, substantially lilling the spacesbetweenl the reduced portions of adjacent workpieces with inserts of lowresistivity, non-magnetic material, passing the workpieces betweenconductors of an inductor, and energizing the inductor with alternatingcurrent.

The primary object of the present invention is the pro vision of anapparatus and method for inductively heating 'simultaneously the reducedportions of a plurality of workpieces by a surrounding inductor 'whichapparatus and method result in a higher eciency than was obtainable withknown' apparatus and procedures.

Another object of the present invention is the provision of an apparatusand method for inductively heating Simultaneously the reduced portionsof a plurality of Workpieces by a Surrounding inductor which apparatusand method limits the amount of rotation of the workpieces which isnecessary as they move through the inductor.

Yet another object of the present invention is the provision of anapparatus and method for inductively heating simultaneously the reducedportions of a plurality of workpieces by a surrounding inductor whichapparatus and method includes the provision of a loW resistivity insertbetween adjacent workpieces and in the space caused by the reducedportions. l

A further object of the present invention is the provision of anapparatus and method #for inductively heating simultaneously the reducedportions of a plurality of workpieces by a Surrounding inductor whichapparatus and method prevents substantial vacant volume within thevolume dened by the inductor.

These and other objects and advantages will become apparent from thefollowing description used to illustrate the preferred embodiment of theinvention as read in connection with the accompanying drawings in which:

FIGURE l isa pictorial, partially c ut away view showi-ng somewhat'schematically' the prior art to which the lpresent invention isdirected;

i Referring now to the drawings wherein the showings are for the purpose'ot illustrating la preferred'embodiment of the invention -only 'and notfor the purpose of limiting same, FIGURES l and 2 illustrate the priorfart to which the present invent-ion is'di-re-cted which prior ,artincludes an apparatus A for induetively heating simultaneously thereduced l:portions of side-by-side worldpieces B. Although it isappreciated that the workpieces may take a variety of structural shapes,the wonkpieces in @accordance with the illustrated embodiment of thepresent invention include gear blanks having flanges ld rand Shanks 12which flanges have a larger transverse dimension than the Shanks.

The .gear blanks B I'are l'received Within a guideway d4 which may beinclined so that the 'gear blanks slide through the lguideway withoutrotation. Also, the guideway may be placed edgewise aswell as beinginclined so that thev gear blanks both rotate and slide along theguideway so th'at the shanks 12 |are uniformly heated in "a `manner tobe hereinafter 'described in detail. yThe tguideway indludes spaced.shoulders 16, 1-3 which deiine Ta guide slot 20 having a dimensionwhich will rece-ive `the dange l0' ot blanks B so that the shanks 12extend youtwardly from the guideway 14 with the shanks beingsubstantially parallel.

The |apparatus :A is yadapted to heat the outermost portion orf shank 12`so that the end of the shank inlay be annealed, hardened or otherwiseheat treated. To accomplish this heating operation, there is providedIan inductor 30 having spaced parallel oonduictors 32, A34 positioned onopposite 'sides of the v-shtanks l2. The indiretto-r 30 is characterized-a-s having a channel 36 rfor allowing movement of the Shanks `1.2through the inductor While the shanks are vin inductive relationshipwith the conductors :312, 34. 'To power the inductor 30, there isprovided ya power source 3S which, in laccordance with the preferredembodiment ot the present invention, is la motor generator setdeveloping three lor ten kc. alternating eurrent. It is appreciatedlthat the inductor i3() may yhave multi-ple turns or may Ibe wider in anaxial 'direction with respect to the Shanks 12 so 'a greater portion ofthe lShanks lare in inductive relation-ship with the inductor. Thesingleturn indu'ctor 30 is shown only for representative purposes and variousother inductors can be provided for simultaneously heating Shanks l2 orsimilar reduced porti-onsA `on other workpieces. Y

In 'operation of the prior 'ar-t device as shown in FIG- URES .1 fand 2,the gear blanks B are moved through the channel 56 of Vivndufctor 30 bysliding the blanks along guideway 114. Since the flanges 10 have algreater transverse dimension than s-hanks l2, there is a considerablevacant space or volume between adjacent Shanks 12. Thus, when :currentllows through the conductors 3.2, 34 as shown in FIGURE 2, an inducedvoltage is developed on opposite sides of Shanks I2 which inducedvoltage causes a heating current to flow inthe portions of the shank -12ladjacent the conductors 3K2, 34. Accordingly, only those portions otthe Shanks adjacent the conductors are ydirectly heated and the`remainder of the shank must be heated by conduction. rltlhis isinefficient `and requires a considerably time delay `ttor stabil-izationot the temperature within the shank `12. Ifthe sh'an-k l2 is to behardcned, then this localized heating may be even more troublesomebecause the shank must beV Iraised to a high temperature 4quickly thenimmediately quenched. To overcome this disadvantage, the blanks B may berotated so various portions 'of shank l2 are in .close proximity withthe .conductors 32, 34. This requires, in Amost instances, a morecomplicated arrangement for moving the gear blanks B through the channel`3rd. In addition, since there is a-lc-onsiderable amount of vacantspace in ehannel 36, the heating eiiiciency of inductor 3d is reduced.

These `disadvantages fare `overcome .by the present invention which isillustrated in FIGURES 3 and-4 wherein inserts 4t) lare positionedbetween the Shanks 12 as the gear blanks move along gui-deway i4. 'Theseinserts are formed from a low resistivity, non-magnetic material such ascopper. ln :accordance with the illustrated embodiment of the presen-tinvention, the blocks du lare rectangular in cross section; however,they are so dimensioned to substantially till rthe spaces between*adjacent `Shanks I12 as is shown in FIGURE 4. It is appreciated thatthe inserts 4) could have various other configura-tions so that theywould till a `greater portion ot the space left vacant because of thedifference in diameter of the AShanks 12 and flanges lll.

In some eases, the inert 'may be magnetic; however, this results in laloss tot efficiency and somewhat offsets the `advantage ot the insert.With a magnetic insert, the workpiece ycan still be heated withoutdrastic rotation.` In addition, the insert will lose its magneticcharacteristics when .heated above the Curie point Kfor the materialforming the inserts.

As shown in FIGURES 3 tand 4, when the gear blanks B slide along theguideway 14 past inductor 3Q, the inserts 4t? `are positioned betweenthe adjacent Shanks 12. rIlhe inductor is energized `and current tiowsthrough lconductors 32, 34 as indicated by the arrows. This now ofcurrent in t-he conductors causes fa corresponding current iiow in theinsert 40 yas .shown in FIGURE 4. 'Ilhe ourrent ii'ow through theinserts 4t) in turn Icauses .a corresponding ourrent how within theShanks 12. Consequently, there is an 'even distribution of current flowaround the periphery of lshank 12 so .that the `Shanks need not [berotated to a great extent las they pass longitudinally through the.channel 36 ot' energized induotor St). It `may be necessary to rotatethe blanks `B slightly to obtain complete uniformity ot currentdistribution through the .peripheiy of shank l2; however, if :conductor-is relied upon for even distribution of vheat through sha-nks 12,conduction takes place quite .rapidly because there are only la fewareas where the current density is substantiallyr reduced.

With the spaces betweenthe Shanks 12 lle'd by the low resistivity,non-'magnetic inserts di?, the eiciency of vthe inductor .Btl issubstantially higher than the etliciency of the inductor when the spacesbetween the 'shanks are vacant.

It is appreciated that the invention has been described in iconnectionwith the use of the inserts ttl betweenY Shanks 12 of gear blanks B;however, these inserts could be used between the reduced ends of axlevshafts and transmission shattts las well a-s between the reduced endsoi various other workpieces as they are progres-sed through a channelinductor. The present invention has been described in connection with`centain Istructural embodiments; however, various modifications inthese embodiments can be `made without `departing from the intendedspirit `and scope of the Jpresent invention as vdefined in the appendedClaims.

Vl-ifzwing thus `described 'my invention, I claim:

l. in an apparatus for simultaneously heating aligned reducedImorti-'ons of a plurality of side-by-'side workpieces includ-ing aninductor having Ea conductor extentling along each side of the reducedaligned portions, 'the improvementoomprising: a low resistivity,non-magnetic insert between adjacent reduced portions, said insert-ssubstantially filling the space between said adjacent reduced portions.

2g. The improve-ment yas defined in claim ,l wherein said inserts 'areformed from `coppe-r.

3. An apparatus tf'or simultaneously heating the aligned reducedportions of a plural-ity of side-by-side workpieces including `aninductor with .spaced parallel conductors, a mean-s for supporting saidworkpieces with .Is-'aid reduced portions aligned, means for 'movingsaid aligned portions between said spaced conductors, a Ilowlresistivity insert between said workpieces Iand .filling the spacesbetween said aligned reduced portions, said inserts being movable withsaid workpie'ces, vand la high frequenlcy power source for energizingsaid inductor yas said work-pieces are passing through said conductors.

4. An apparatus as dened in claim 3 wherein said inserts arenon-magnetic.

S. An apparatus a-s dened in claim 4 wherein said inserts fare formedfrom copper.

y6. An apparatus as deiined in claim 3 wherein said supporting means isa `guideway having means for allowing said workpieces Ito slide throughsaid gfuideW-ay :with said reduced portions extending between saidconductors.

7. A 'method ifor simultaneously heating the reduced porti-ons of aplurality of workpieces comprising, aligning the Workpielces inside-lby-side relationship with the reduced portions aligned to producespaces between the reduced portions of adjacent worhpieces,substantially lling said spaces between the reduced portions of adjacent6 Workpieces with inserts of lo-W yresistivity material, passing theworkpieces between conductors of lan inductor, and energizing saidinductor with alternating high frequency current.

References Cited by the Examiner UNITED STATES PATENTS 15 RICHARD M.WOOD, Primary Examiner.

L. H. BENDER, Assistant Examiner.

1. IN AN APPARATUS FOR SIMULTANEOUSLY HEATING ALIGNED REDUCED PORTIONSOF A PLURALITY OF SIDE-BY-SIDE WORKPIECES INCLUDING AN INDUCTOR HAVING ACONDUCTOR EXTENDING ALONG EACH SIDE OF THE REDUCED ALIGNED PORTIONS, THEIMPROVEMENT COMPRISING: A LOW RESISTIVITY, NON-MAGNETIC INSERT BETWEENADJACENT REDUCED PORTIONS, SAID INSERTS SUBSTANTIALLY FILLING THE SPACEBETWEEN SAID ADJACENT REDUCED PORTIONS.